Sewing machine

Abstract

A lower end of a thread guide lever, which is rockably attached to a lower looper and supports a thread pipe, and an air ejecting unit, which faces a thread inserting hole of the thread pipe and ejects air toward the thread inserting hole, are coupled via a coupling member so that they are interlocked with each other. The coupling member is moved such that a discharging port of an air nozzle is positioned at an ejecting position close to the thread inserting hole when a thread discharging hole is positioned at a threading position which is coincident with a thread hole of a lower looper, and such that the air nozzle is moved to a standby position when the thread discharging hole is moved to a retreating position.

1 . A sewing machine comprising:
 a looper driving mechanism including a looper, wherein the looper is formed with a thread hole at a tip portion thereof, and the tip portion of the looper is adapted to be inserted into a loop of a needle thread by moving the tip portion back and forth in synchronization with a vertical motion of a needle;   a thread path member having one end formed with a thread inserting hole, the other end formed with a thread discharging hole, and a thread path inside which a lower looper thread is able to be inserted;   thread path member moving means for moving the thread path member such that the thread discharging hole is moved between a threading position, at which the thread discharging hole becomes coincident with the thread hole of the looper, and a retreating position placed apart from the threading position;   air ejecting means for ejecting air toward the thread inserting hole, wherein the air ejecting means is disposed so as to face the thread inserting hole;   air supplying means for supplying the air to the air ejecting means;   air ejection moving means for moving the air ejecting means between an ejecting position adjacent to the thread inserting hole and a standby position placed apart from the ejecting position; and   interlocking means for interlocking the thread path member moving means and the air ejection moving means such that the air ejecting means is positioned at the ejecting position when the thread discharging hole is positioned at the threading position.   
   
   
       2 . The sewing machine according to  claim 1 , wherein the interlocking means includes:
 a first actuator which drives the thread path member moving means;   a second actuator which drives the air ejection moving means; and   interlocking control means for driving the first and second actuators such that the thread path member moving means and the air ejection moving means synchronize with each other.   
   
   
       3 . The sewing machine according to  claim 1 , wherein the interlocking means includes a coupling member which couples the thread path member moving means and the air ejection moving means. 
   
   
       4 . The sewing machine according to  claim 1 , wherein the interlocking means includes an actuator which drives at least one of the thread path member moving means and the air ejection moving means. 
   
   
       5 . The sewing machine according to  claim 2 , wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle,
 wherein the sewing machine further comprises:   input means for inputting an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper;   spindle angle detecting means for detecting that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and   ejection control means for stopping the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting means and for driving the second actuator to position the air ejecting means at the ejecting position when the instruction to start the threading operation is input from the input means.   
   
   
       6 . The sewing machine according to  claim 4 , wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle,
 wherein the sewing machine further comprises:   input means for inputting an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper;   spindle angle detecting means for detecting that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and   ejection control means for stopping the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting means and for driving the actuator to position the air ejecting means at the ejecting position when the instruction to start the threading operation is input from the input means.   
   
   
       7 . The sewing machine according to  claim 1 , wherein the sewing machine further comprises returning means for positioning the thread discharging hole of the thread path member at the retreating position in accordance with a drive of a sewing machine motor. 
   
   
       8 . A sewing machine comprising:
 a looper driving mechanism including a looper, wherein the looper is formed with a thread hole formed at a tip portion thereof, and the tip portion of the looper is adapted to be inserted into a loop of a needle thread by moving the tip portion back and forth in synchronization with a vertical motion of a needle;   a thread pipe having a thread path inside which a lower looper thread is able to be inserted, wherein the thread path connects a thread inserting hole and a thread discharging hole, and the thread pipe is arranged such that the thread discharging hole is movable between a threading position a threading position, at which the thread discharging hole becomes coincident with the thread hole of the looper, and a retreating position placed apart from the threading position;   a thread pipe moving mechanism which is coupled to the thread pipe and is operable to move the thread discharging hole between the threading position and the retreating position;   an air ejecting unit which is movable between an ejecting position, at which the air ejecting unit faces the thread inserting hole and ejects air toward the thread inserting hole, and a standby position placed apart from the ejecting position;   an air supplying unit which supplies the air to the air ejecting unit;   a air ejection moving mechanism which is coupled to the air ejecting unit, and operable to move the air ejecting unit between the ejecting position and the standby position; and   an interlocking mechanism operable to interlock the thread pipe moving mechanism and the air ejection moving mechanism such that the air ejecting unit is moved from the standby position to the ejecting position when the thread discharging hole is moved from the retreating position to the threading position.   
   
   
       9 . The sewing machine according to  claim 8 , wherein the interlocking mechanism includes:
 a first actuator which drives the thread pipe moving mechanism;   a second actuator which drives the air ejection moving mechanism; and   an interlocking control portion operable to drive the first and second actuators such that the thread pipe moving mechanism and the air ejection moving mechanism synchronize with each other.   
   
   
       10 . The sewing machine according to  claim 8 , wherein the interlocking mechanism includes a coupling member which couples the thread pipe moving mechanism and the air ejection moving mechanism. 
   
   
       11 . The sewing machine according to  claim 8 , wherein the interlocking mechanism includes an actuator which drives at least one of the thread pipe moving mechanism and the air ejection moving mechanism. 
   
   
       12 . The sewing machine according to  claim 9 , wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle,
 wherein the sewing machine further comprises:   an input portion form which an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper is input;   a spindle angle detecting sensor which detects that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and   an ejection control portion which stops the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting sensor and drives the second actuator to position the air ejecting unit at the ejecting position when the instruction to start the threading operation is input from the input portion.   
   
   
       13 . The sewing machine according to  claim 11 , wherein a driving force is applied to the looper from a sewing machine motor via a looper shaft which is interlocked with a spindle,
 wherein the sewing machine further comprises:   an input portion form which an instruction to start a threading operation for inserting the lower loop thread through the thread hole of the looper is input;   a spindle angle detecting sensor which detects that the spindle rotated by the sewing machine motor is positioned at a predetermined rotating angle; and   an ejection control portion which stops the spindle at the predetermined rotating angle based on a detection of the spindle angle detecting sensor and drives the actuator to position the air ejecting unit at the ejecting position when the instruction to start the threading operation is input from the input portion.   
   
   
       14 . The sewing machine according to  claim 8 , wherein the sewing machine further comprises a guide member which positions the thread discharging hole at the retreating position in accordance with a drive of a sewing machine motor.